Pressure contour human restraint



Feb- 13, 1968 R.. E. VAN PATTEN 3,368,222

PRESSURE CONTOUR HUMAN RESTRANT l Filed Feb. 1o, 196e 2 shetS-sneex'l Feb. 1 3, 19.68 R'. E. VAN PATTEN 3,368,222

PRESSURE CONTOUR HUMAN RESTRAINT Filed Feb. 1o, 1966 2 sheetssheet 2 United States Patent Office 3,368,222 PRESSURE CONIGUR HUMAN RESTRAINT Robert E. Van Patten, Dayton, Ohio, assigner to the United States of America as represented by the Secretary of the Air Force Filed Feb. 10, 1966, Ser. No. 526,634 1 Claim. (Cl. 2-22) ABSTRACT F THE DISCLSURE A protective restraint for the knee and lower leg sections of an astronaut to protect him from strain imparted by straps and increased gravitational stress. The restraint constitutes a covering having a fiberglass shell fitted to the front part of the leg but spaced therefrom at Varying distances depending on the thinness of tissue overlying the sensitive bone structure. The less the tissue, the greater this distance. The space between the shell and the leg is filled with a padding formed yof foamy material which will compress at a fast rate but will be restored to its original shape quite slowly. Thus any stresses set up over the tibia bone or other sensitive areas by straps, etc. are distributed over the entire surface of the leg. The shell is held in place at the rear by attaching nylon mesh sections each of which are fitted to a zipper unit.

The invention described herein may be manufactured and used -by or for the United States Government for governmental purposes without the payment to me of any royalty thereon.

The present invention relates to bio-dynamic restraint systems, particularly as applied to the knee and lower leg sections of the human body when subjected to increased gravitational stresses.

In the field of aerospace manned systems in whi-ch the astronaut is constrained by mechanical devices or straps to one position for long periods of time, comfort and tolerance are in significant ways limited by the squeezing of blood from tissues subjected to concentrated pressure of the straps or other restraining devices. The latter is necessary in order tol protect the subject from injury in the event of sudden changes in direction of movement of the vehicle, fast acceleration or deceleration, also sudden changes in position of the vehicle.

Moreover, when the astronaut is under increased gravitational stress, such as l0 Gs (l0 times gravity), due to rotation about any one or more of the horizontal or vertical axes while restrained in a rigid position by the straps, the stresses set up against the limbs may become so great at or near the binding element as to lead to numbness, and finally to pain in the affected part of the body.

Generally, the areas of most intense distress or discomfort are those in which the thickness of tissue overlaying a bone area is quite small. The present invention therefore involves, in large degree, the pressure point discomfort resulting from the application of conventional supports or restraints.

Inasmuch as the legs or feet of an astronaut, when in a seated position, extend further from the imaginary z or vertical spin axis, than the other parts of the body, and hence are subjected to maximum stress in the horizontal direction, as when the plane is in a yaw movement, the invention is directed mainly to the leg restraints, although the principle involved applies to other restrained parts of the body.

One object of the invention is to provide an improved structure which can be used with conventional restraints over long periods of time without the normal discomfort of such restraints and can withstand considerable 3,368,222 Patented Feb. 13, 1968 gravitation stress, regardless of the direction and manner in which the force is applied.

Another object is to provide an improved accessory used with a conventional restraint, especially for the lower parts of the legs of an astronaut to avoid any discomfort when subjected to stresses brought about by the ever-changing movements of a space vehicle in terms of gravitational values.

The objects are attained in brief by providing a basic support structure modeled to the surface of the body segment to be restrained and padding the structure in Varying thicknesses, in inverse proportion to the thickness of tissue lying between the bone and the flesh at the position of the conventional restraint.

Thus, where the tissue is thinnest, the support becomes the thickest and where the tissue is considerable, the re- .siliency and thickness of padding is reduced.

The invention will be better understood when reference is made to the following description and the accompanying drawings in which:

FIG. l represents as a diagram, the movement of the various parts of the body when subjected to a spin effect;

FIG. 2 is a sketch made from a photograph of the lower part of an astronauts body in which knee and foot restraints are provided in addition to the improved lower leg support;

FIG. 3 represents a transverse cross section of a typical human leg and a section of the padded portion of the improved shell surrounding the leg; and

FIGS. 4 and 5 show, in perspective, the open and closed positions of the improved support or accessory restraint.

Referring to FIG. l, there is shown some of the forces acting on a human body when spinning about the vertical axis, Rz, the resulting movement of his extremities being shown in dot-dash line with accompanying explanation. The spinning action is intended to emulate the force applied to an astronauts body when subjected to a sudden yaw effect of the airplane or a steep accelerating or decelerating movement. The spinning effect also provides changes in gravitational stress introduced by centrifugal force as the rotation is increased with corresponding increase in the magnitude of G along a horizontal axis Rx passing through the torso from back to front.

It will be noted that the lower legs to which this invention is `directed tend to swing upwardly together as indicated by the arrow a and outwardly as the magnitude of G increases. It therefore becomes necessary to apply a support not only to each leg but -also to the feet and possibly the knees. However, the greater amount of restraint must be applied to the legs in particular, since they tend to move forwardly and outwardly in greater distance when a centrifugal force is applied. A stress of this type would be set up by a forward or backward acceleration in the horizontal direction of the plane, or perhaps a tight roll.

Various conventional restraints have been proposed, most of which include straps binding the legs tightly to the seat. In the absence of the improved support to be described hereinafter the press-ure exerted by the restraining straps about the legs may lead from discomfort to numbness and finally to pain, all of which symptoms are aggravated when the astronaut is undergoing gravitational stresses.

In accordance with the present invention, .an improved support, particularly for the lower part of the legs is disclosed which not only takes into account the configurathe ilegs circumference. The edge of the shell at each side is flared outwardly at 3 to avoid any possible inward pinching effect. The finished shells are provided along the interior surface throughout the length with a padding material 4 varying in thickness from 1/2 to l according to the thinness of the issue overlying a sensitive bone structure or a relatively solid muscle mass. The padding may constitute a foamy material of the polyurethane group which has a high hysteresis factor in that it will compress at a fast rate but will be restored to its original (uncompressed) shape quite slowly. This will prevent a fast spring-back action after the compressing effect. A padding sold on the market under the name Ensolite makes excellent material for this purpose.

The distribution of the padding is diagrammatically indicated in FIG. 3 and, as illustrated, the padding has a thickness in inverse proportion to the thickness of tissue overlying the front interior members of the leg, especially the tibia bone. The latter appears to take the brunt of any concentrated pressure at the front part of the leg and attempts to pass on most of the compressional force to the other parts of the leg. Thus, any stresses set up in the leg by reason of the restraints, straps, etc., are distributed over the entire surface of the leg but are temporarily concentrated at the tibia or other sensitive areas.

Again referring to FIG. 3, it will be noted that the thickest part of the padding or resilient material is at the front of the leg, directly above the small rounded portion of the tibia. The padding becomes of less thickness along both sides because, at these areas, the tissue is thicker than at the anterior of the leg and the gravitational pressure is less since it is closer to the Rz axis. The thinnest layer of padding is found at or near the edges of the shell 1 where the thickness of the tissue is the greatest and the gravitational pressure becomes the least.

The shells are held in position by attaching nylon mesh sections 5 sewn together at each seam 6 as shown in FIG. 4. A strong piece of cloth 7 is secured to the edge of the outer mesh section for receiving a part 8 of a zipper unit. A strip of industrial cloth 9 is attached in any suitable manner to the opposite edge of the shell for carrying the other part 10 of the zipper unit. Thus, the shell can be fitted against each leg as shown in FIG. 2 and closed by the zipper. A wide strap restraint 11 fastened at each side of the astronauts seat can be drawn by the buckles 12. As shown in FIG. 2, knee straps 13, and boot straps 14, can also be applied to hold the lower part of the astronauts body firmly in his seat.

Method for forming the shells While it is preferabie to custom make the shells or supports to conform to the leg requirements of the particular astronaut, it has been found that the leg sizes may be divided generally into three typical groups: large, medium, and small. The shells can therefore be molded as explained hereinafter to t quite comfortably any size of astronaut, particularly in view of the contained padding. The subject would be seated (on an elevated platform) in a chair with his legs placed in simple box-like molds. The molds would be band-sawed to the approximate transverse contour of the subjects legs with the anterior halves of his legs enclosed in the molds. The approximate contouring can be done after the modelrnaker has traced the outline of the inside and outside of the legs on the wood.

The molds could then be lled with a mixture of clean, common core sand and .a liquid binder of the sodium silicate group added. It has been found that a binder sold under the name Steinex gives satisfactory results. After the mixture is tamped to a consistent density, carbon dioxide is bled through the mixture, resulting in a chemical reaction with the binder. This reaction transforms the mixture into a rigid mass forming an accurate replica of the contour of the leg. Instead of a sand mold, it may be desirable to form a mold formed of plaster of paris or other suitable hardening material.

The hardened sand mold would then be coated with a suitable resin, such as a polyester, to provide a somewhat glassy surface from which a male plaster of paris cast could be formed. The plaster cast would then be coated with slab-like layers of modeling clay representing the various thicknesses of the padding determined by a tissue study of the leg in order adequately to distribute the acceleration loads in accordance with the invention.

A number of plies of an industrial grade of glass ber cloth would be impregnated with a suitable and wellknown resin, as many as desired, to make the full thickness of the shell. These plies can be individually pressed against the mold thus established, and the ensuing chemical reaction would cause the shell portion to meld together into a solid, rigid form which closely follows the contour of the mold. The varying thicknesses of padding in the form of strips would then be placed within the completed shell and secured by bonding, these strips having varying thicknesses to fill the recesses left by the impressions of the modeling clay.

The nylon mesh rear cover can then be secured, for example, by bonding, along one edge of the shell to engage the other edge.

It is evident that the pressure contour proportioning principles disclosed herein which take into account, not only the configuration of the body surface or segment being supported or restrained, but also the pressure concentrations brought about by the gravitational stresses normally suffered over long periods of time, can be used for comfortable seating in aerospace vehicles on extended duration missions, as well as in passenger cars, trucks, tanks, and other land vehicles which may give rise to stresses of this type.

It is also evident that while the invention has been directed more specially to the protection of the lower legs, other parts of the body which are subject to these gravitational stresses and need to be strapped down can also be provided with an improved shell member containing padding of the requisite and varying thickness according to the amount of tissue overlying the bony organic member at the point where the pressure is concentrated.

I claim:

1. A protective device for relieving gravitational stress at the front portion of the leg, said device including a rigid shell surrounding the front portion of the leg and at least partially over the sides of the leg, said shell being spaced from the leg in the region of the front portion at greater distances than at the sides of the leg, the width of the space between the shell and the leg being varied in accordance with the variations of thickness of tissue at the respective positions between the esh and the underlying bone encompassed by the shell structure, a padding completely filling the space between the shell and the leg, and means for holding the device in position on the leg.

References Cited UNITED STATES PATENTS 1,225,354 5/1917 Pierce 2-22 X 2,817,841 12/1957 Bilecki 2-22 3,074,405 1/ 1963 Duensing 2-22 X 3,135,964 6/1964 Pender 2-22 3,189,919 6/ 1965 Chase 2-22 X 3,229,936 1/ 1966 Quillinan 2-2.1 3,295,529 1/1967 Carrigall et al 2 2 HERBERT F. ROSS, Prmaly Examiner. 

